Fountain solution recycling system for commercial printers

ABSTRACT

A method of and apparatus for extending the life of fountain solutions used in commercial printing presses comprises withdrawing fountain solution from the dampener recirculation system of a printing press and directing the withdrawn fountain solution through a sediment prefilter, a separation filter, and a post treatment filter. The sediment prefilter preferably comprises a melt blown polypropylene filter; the separation filter preferably comprises a diatomaceous earth filter; and the post treatment filter preferably comprises a zeolite filter.

TECHNICAL FIELD

This invention relates generally to improvements in commercial printingsystems and more particularly to a system for removing contaminants fromand thereby extending the life of fountain solutions utilized incommercial printing plants.

BACKGROUND AND SUMMARY OF THE INVENTION

A typical offset lithographic printing press has a plate cylinder uponwhich the negative of the text and illustrations to be printed areetched by a photographic and/or an electronic process. Dampening rollersapply a fountain solution to the plate cylinder which adheres to theplate cylinder except in the areas in which the text and illustrationsare located.

Next, a series of form rollers, also known in the art as inking rollers,apply a layer of ink to the plate cylinder. The ink adheres to the platecylinder only in the etched areas comprising the text and illustrations.

The plate cylinder then presses the inked text and illustrations onto arubber blanket cylinder. An impression cylinder then presses a sheet ofpaper or other substrate to be printed against the blanket cylinder asthe paper or other substrate passes between the blanket cylinder and theimpression cylinder. The inked text and illustrations on the blanketcylinder are transferred onto the paper or other substrate to effectprinting thereof.

Over time, ink, paper fiber, spray powder, and other contaminants buildup in the fountain solution. These contaminants negatively impact printquality. Additionally, as the fountain solution degrades wateradjustments are required. Eventually the fountain solution becomes socontaminated that it needs to be replaced. The present inventioncomprises a system for minimizing fountain solution contaminationthereby extending the useful life of the fountain solution by asubstantial period of time.

The fountain solution recycling system of the present invention utilizesa unique multi-stage separation technology and a recirculation pump toclean and restore the fountain solution. Removal of contaminants isachieved by processing the solution through three separate treatmentstages resulting in a reusable, stabilized fountain solution. Componentsof the fountain solution which are consumed due to carry-off by theprinting substrate and evaporation are replaced in the conventionalmanner.

Use of the fountain solution recycling system of the present inventioneasily and reliably reduces costs and improves productivity in an aspectof the commercial printing business that has traditionally beenneglected. Simply extending the life of the fountain solution typicallyadds 1-2 hours of productivity per week per printing press becausechanging the fountain solution and cleaning the system are no longerrequired.

Additionally, by extending the life of the fountain solution wastedisposal costs associated with fountain solution replacement aredramatically reduced. In those instances in which spent fountainsolution is drained, use of the present invention greatly reduces thecopper, zinc, ink, glycols, phosphates and suspended solids going intothe drain thereby lessening the impact on the environment.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete understanding of the present invention may be had byreference to the following Detailed Description when taken in connectionwith the accompanying Drawings, wherein:

FIG. 1 is a perspective view of a fountain solution recycling system forcommercial printers incorporating the invention; and

FIG. 2 is a schematic illustration of the fountain solution recyclingsystem of FIG. 1 and the interaction thereof with a commercial printingpress.

DETAILED DESCRIPTION

Referring now to the Drawings, and particularly to FIG. 1 thereof, thereis shown a fountain solution recycling system 10 incorporating thepresent invention. The system 10 includes a pump 12 which receivesfountain solution from a commercial printing press through a line 14.The output of the pump 12 is directed to a sediment prefilter 16 througha line 18. The sediment prefilter 16 comprises a housing 20 whichcontains a strainer or filter formed from melt blown polypropylene andhaving a consistency generally similar to that of a fibrous web. Thefunction of the sediment prestrainer 16 is to remove relatively largeparticles from the flowing fountain solution.

From the sediment prefilter 16 the fountain solution is directed to aseparation cartridge 22 through a line 24. The separation cartridge 22comprises a housing which contains a diatomaceous earth filter andfunctions to remove sub-micron sized particles from the flowing fountainsolution. Thus, having passed through the sediment prefilter 16 and theseparation cartridge 22 the fountain solution is substantially free ofparticulate and colloidal contaminants.

From the separation cartridge 22 the fountain solution is directed to apost treatment cartridge 26 through a line 28. The post treatmentcartridge 26 comprises a housing which contains a natural zeolite filtermaterial which removes copper ions, zinc ions, and other ions from theflowing fountain solution thereby substantially removing metal ioncontaminants from the fountain solution. After flowing through the posttreatment cartridge 26 the fountain solution is returned to the dampenerrecirculating device of the commercial pressing press through a line 30.

The sediment prefilter 16, the separation filter 22, and the posttreatment filter 26 comprise a three stage treatment system in whicheach stage has a symbiotic relationship with the former stage. The useof the combined system comprising the prefilter 16, the separationfilter 22, and the post treatment filter 26 affords two highlybeneficial results. First, the use of the combined system substantiallyextends the life of fountain solution flowing therethrough. Second, thecombined system renders the fountain solution much more environmentallyfriendly upon ultimately disposal.

FIG. 2 illustrates the use of the fountain solution recycling system 10in conjunction with a commercial printing press 32. A recirculation pump34 withdraws fountain solution from a fountain solution recirculationtank 36 and directs the fountain solution to one or more printing pressdampener pans 38 as indicated by the arrows 40 and 42. From the printingpress dampener pans 38 the fountain solution is applied to dampeningrollers which in turn apply the fountain solution to the plate cylinderof the printing press 32. In the operation of the printing press 32fountain solution is continuously withdrawn from the printing pressdampener pans 38 and returned to the tank 36 as indicated by the arrows44 and 46.

The fountain solution recycling system 10 of the present inventionwithdraws fountain solution from the tank 36 through the line 14 andreturns the fountain solution to the tank 34 through the line 30. Thus,the system 10 of the present invention functions to maintain thefountain solution within the tank 36 in a substantially clean conditioncharacterized both by a lack of particulate contamination and areduction of metal ion contamination.

As is best known in FIG. 1, the components of the fountain solutionrecycling system of the present invention may be mounted on a pallet. Bymounting all of the components of the system on a pallet installation ofthe system at convenient location within a commercial printing plant isreadily accomplished. All that remains to be done is the connection ofthe lines 14 and 30 to one or more printing presses within the plant,whereupon operation of the system can be commenced.

EXAMPLE

A typical eight-color 40″ printing press requires the disposal of about40 gallons of fountain solution per week, or about 2100 gallons peryear. 2100 gallons equals about 40 barrels of spent fountain solutionthat must be disposed of annually. At a typical disposal cost of about$250/barrel the annual fountain solution disposal cost is about $10,000per year per printing press. Conversely, when the present invention isused the annual fountain solution disposal requirement is about 2barrels or about $500 per year per press. Elimination of press downtimefor fountain solution change out is another benefit resulting from theuse of the present invention. At just one hour of eliminated downtimeper week the use of the present invention saves over $15,000 per yearper press. When down time savings are combined with disposal costsavings use of the present invention results in about $25,000 in annualsavings per press.

Although preferred embodiments of the invention have been illustrated inthe accompanying Drawings and described in the foregoing DetailedDescription, it will be understood that the invention is not limited tothe embodiments disclosed, but is capable of numerous rearrangements,modifications, and substitutions of parts and elements without departingfrom the spirit of the invention.

1-25. (canceled)
 26. A method for maintaining the quality of commercialprinting press fountain solution circulated through a printing press ofthe type having a fountain solution circulation system comprising afountain solution recirculation pump for withdrawing fountain solutionfrom a fountain solution tank and circulating the fountain solutionthrough the printing press and back to the fountain solution tankcomprising the steps of: providing side stream loop means independentfrom the fountain solution circulation system; providing means forremoving particulate matter from the fountain solution; utilizing theside stream loop means to withdraw fountain solution from the fountainsolution tank and thereafter directing the withdrawn fountain solutionthrough the means for removing particulate matter from the fountainsolution; and returning the withdrawn fountain solution from theparticulate matter removal means to the fountain solution tank of thefountain solution circulation system.
 27. The method according to claim26 wherein the means for removing particulate matter from the fountainsolution comprises at least one filter housing having a filter containedtherein.
 28. The method according to claim 26 wherein the means forremoving particulate matter from the fountain solution comprisesmultiple separate and distinct filter housings each having a filtermounted therein.
 29. The method according to claim 28 wherein themultiple separate and distinct filter housings each having a filtermounted therein comprise a three-stage treatment system with each stagehaving a symbiotic relationship with the former stage.